The vagus nerve is the 10th cranial nerve in the body. Vagus nerve stimulation, and the profound effects of electrical stimulation of the vagus nerve on central nervous system (CNS) activity, extends back to the 1930's. Medical studies in clinical neurobiology have advanced our understanding of anatomic and physiologic basis of the effects of vagus nerve stimulation.
Afferent neuromodulation of the vagus nerve has clinical efficacy for various neurological and neuropsychiatric disorders, such as partial complex epilepsy, generalized epilepsy, parkinsonson's disease, migraines, severe depression, Alzheimer's disease, anxiety disorders, obsessive compulsive disorders, and the like. Prior art discloses implanted pulse generator (IPG) system, and inductively coupled system using an implanted stimulus receiver and an external stimulus transmitter.
An IPG system for neuromodulation granted to Zabara U.S. Pat. Nos. 4,702,254, 4,867,164, and 5,025,807, discloses essentially “cardiac pacemaker-like” technology applied to stimulating a vagus nerve. Such system and method, though convenient has the disadvantage that internal battery will not last for a desired period of time, which can lead to repeated surgeries for generator replacement. Also, because of the concern for battery longevity, optimal therapy for giving electrical pulses is usually not utilized since that would lead to excessive battery drain. Further, the programming of the stimulation parameters is performed by the medical staff and requires a visit to the physician's office or the clinic when a program change has to be made. Thus, the prior art has a cumbersome process of adjusting the therapy levels.
An inductively coupled system and method for neuromodulation granted to Boveja U.S. Pat. Nos. 6,205,359 B1, 6,269,270 B1, and 6,356,788 B2 overcomes many of the disadvantages of an IPG system such as battery life, and easier activation of programs by the patient, but patient convenience remains an issue since a secondary coil has to be kept in close proximity to an implanted primary coil. It would be desirable to have the advantages of both an IPG system and an inductively coupled system. The system and method disclosed, provides an improved method and system for adjunct therapy by providing a system that has the benefits of both systems, and has additional synergistic benefits not possible in the prior art. In this application the patient can choose when to use an external inductively coupled system to conserve the battery life of the implanted module and receive higher levels of therapy.
The current application discloses an implanted medical device capable of being used as a programmable implanted pulse generator (IPG), or as a stimulus-receiver for an inductively coupled system with power being supplied by an external stimulator, as is shown in FIGS. 1 and 2. The external stimulator also being remotely controllable from a distant location via the internet. Controlling circuitry within the device, makes the inductively coupled stimulator and the IPG operate in harmony with each other, as described later. For example, when stimulation is applied via the inductively coupled system, the battery operated portion of the stimulator is triggered to go into the “sleep” mode. Conversely, when programming pulses (also inductively coupled) are being applied to the battery operated pulse generator, the inductively coupled stimulation circuitry is disconnected.
In the method and system of the current invention, after the system is implanted in the patient, optimal stimulation parameters are “titrated” for the condition of the individual patent. Clinical research has shown that each patient is biologically unique and responds little bit differently to given stimulation. The inductively coupled stimulation part of the system is a very convenient method of adjusting the parameters for stimulation therapy, that would be optimally suited for each individual patient. Further, as shown in FIG. 3, the external stimulator has a telemetry module and can be controlled remotely via the internet. In one embodiment, numerous pre-determined programs are pre-packaged into the memory of the external stimulator 42. A physician situated remotely is able to selectively activate (and de-activate) selected pre-packaged (pre-determined) programs. As shown in FIGS. 4A and 4B, the telemetry module within the external stimulator wirelessly communicates with a base station 2, either via a server (shown in FIG. 4A) or directly (shown in FIG. 4B). Also, as shown in FIG. 5, a physician in a remote location is able to interrogate and selectively program the external stimulator 43 via a server 130.
Once the appropriate stimulation parameters are determined by “trial and error”, the battery operated portion of the implanted pulse generator can be programmed to the optimal electrical stimulation parameters via a programmer 85. For ideal therapy the electrical stimulation parameters need to be adjusted at regular intervals taking into account optimal benefits.
Another distinct advantage of the current system is that when the stimulation is performed via the external stimulator 42, the battery of the implanted pulse generator (IPG) 70 is conserved, extending the life of the implanted system.